Chula Vista Elementary School officials are suing the federal Department of Justice, trying to figure out why no red flags came up when the district went to hire a teacher who had been involved in a child pornography ring.

The lawsuit filed in San Diego federal court on Tuesday says the government has refused to even acknowledge it made an immunity deal more than 15 years ago with the man, 42-year-old John Kinloch.

The deal had been reported in the media as far back as 1998, and Kinloch himself testified about it in court.

Kinloch was arrested in December and charged with molesting a former student and persuading other boys to send him nude photographs. He pleaded not guilty and is on unpaid leave from his job as a teacher at Wolf Canyon Elementary School.

The district says it needs the federal documents to figure out why Kinloch’s past did not come up in the background check it conducted before he was hired, and determine whether any legislative fixes could prevent a repeat in the future.

The Justice Department cited a provision of the federal Freedom of Information Act that said confirming or denying any records of a deal with Kinloch would “constitute a clearly unwarranted invasion of personal privacy.”

The department refused requests to turn over information, and last week declined to comment because of the pending litigation.

“We would hope the Department of Justice would share our concerns of preventing this from ever happening again,” school district spokesman Anthony Millican said. “Why did the background check fail? We need their records to explain how this happened, so we can change it and stop it from happening again.”

Kinloch was hired by the district in 2000 and taught at two schools, most recently at Wolf Canyon.

Two years before he was hired, Kinloch testified in a trial in England against a man charged with what was then the relatively new crime of transmitting child pornography over the Internet. The investigation into the man in England led police to Kinloch, who would later testify he had traded child pornography with the man since 1995.

Kinloch struck a bargain with U.S. authorities: He would get immunity here from child pornography charges, so long as he went to England and testified. The agreement wasn’t really a secret, since Kinloch spoke about it in open court.

“They said they would not prosecute me if I told the truth and cooperated,” he testified, according to a news account of the trial in a British newspaper.

Also, the San Diego Reader in 1998 published a story about the case and Kinloch’s role, quoting Mitchell Dembin, the prosecutor who arranged the plea deal and is now a U.S. Magistrate Judge in San Diego.

When Kinloch returned to the states, he completed his course work at San Diego State University and got a teaching credential. When Chula Vista hired him in September 2000, nothing about his involvement in the ring, or the immunity agreement, turned up in his background check.

That could be because Kinloch was never formally charged here, so no court or arrest record would be in the system. The news stories did not turn up because the district did not conduct Internet searches then on potential employees and does not now. Background checks for teachers in California are handled throgh a program administered by the state Department of Justice when applicants apply for teaching credentials.

The exact reason the background check didn’t uncover Kinloch’s past isn’t known, and the district wants to find out. It wants copies of the immunity arrangement as well as any correspondence with the department and with officials from Great Britain.

The public interest in knowing those details of far outweighs any privacy interest, the district contends. Millican said that the public relies on the integrity of background checks to identify people like Kinloch, who testified that he was attracted to boys who were teenagers, and younger.